Locking fastener assembly

ABSTRACT

A locking fastener assembly comprising a nut and a washer. The nut and washer each have opposed load bearing surfaces which include a series of annularly extending, slightly inclined faces forming shallow undulations around each surface. The load bearing surface on the nut is generally spherically convex and the load bearing surface on the washer is generally spherically concave. The nut rotates as it is installed while the washer is prevented from rotating so that the undulating bearing surface on the nut slides over the undulating bearing surface on the washer against ever increasing resistance until the assembly is properly seated and the nut is effectively prevented from counter-rotating by interference between opposed, inclined faces. A concave clamping surface is formed on the outer end of the washer on a radially extending flange. The flange flexes when the assembly is installed and resiliently urges the washer against the nut.

FIELD OF THE INVENTION

[0001] This invention relates generally to threaded fasteners. Itrelates particularly to locking fasteners of the type employing athreaded nut and a locking washer.

BACKGROUND OF THE INVENTION

[0002] A locking fastener or locking fastener assembly is employed toprevent loosening of a threaded fastener element in a fastener joint.There are numerous types of joints in which locking fasteners orfastener assemblies are not only desirable but necessary to prevent anut from loosening. One such application is in the axle and wheel nutassembly of a motor vehicle or the like.

[0003] In a typical axle and wheel nut assembly, the hub is supported ona spindle by axle bearings which permit the hub, and thus a vehiclewheel, to rotate on the spindle. An axle bearing nut is threaded ontothe free end of the spindle and holds the axle bearings and bearingraces together in a predetermined relationship. The axle bearing nutmust be set in precisely the proper position on the spindle to apply endloading on the bearing races sufficient to avoid excessive play in thebearings but insufficient to overload them, the result of either beingpossible bearing failure or even loss of a wheel.

[0004] Numerous types of nuts with positive locking components are wellknown. One of the oldest and most common of these is the conventionalcastellated nut and cotter pin assembly. The disadvantages of theseassemblies are numerous. They include the necessity of carefullylocating a hole through the axle spindle, of using an extra component,of reduced nut strength, of relatively long installation time and of thedifficulties encountered in fine tuning the preload on the bearingraces.

[0005] Newer developments in locking fastener assemblies include thosefound in the Anderson, Jr. U.S. Pat. No. 3,762,455, the Grube U.S. Pat.No. 4,812,094, the Burdick U.S. Pat. No. 5,533,849, and the PeterkortU.S. Pat. No. 5,597,278, for example. Of these, the Grube and Peterkortpatents are assigned to the same assignee as the present invention, aswill be noted.

[0006] The Peterkort patent discloses a locking fastener assemblyconsisting of a flanged nut and a retainer washer loosely seated on thenut's flange. The retainer washer includes a radially inwardly extendingtab which is designed to slide axially along a slot in a threadedspindle while preventing the washer from rotating relative to thespindle. A releasable locking clip is positioned to lock the nut to thewasher. The locking clip is released by engagement of a wrench socketwith a hex-head on the nut so that the nut can be threaded to a desiredbearing loading position. When the wrench is removed, the clipinterlocks the washer and nut to prevent the nut from rotating.

[0007] The aforedescribed Peterkort locking fastener assembly is ahighly effective device for use in vehicle wheel assemblies. It issimple and relatively inexpensive. However, its design focuses onlimiting end play, not maintaining a constant preload.

[0008] Other known locking fastener designs include prevailing-torquelocking fasteners. Locking action is achieved with frictional resistanceinduced between mating threads. There is positive resistance toassembly, which maintains throughout fastener seating and tightening. Ahigh residual resistance to loosening remains even if fastener preloadis lost. Disassembly is even difficult. Complete disengagement inservice is highly unlikely. Prevailing-torque fasteners are generallyall-metal fasteners with modified threads or fasteners with a separatenon-metallic element or one fused to the threads. The former have fewertemperature and environmental limitations than the latter, but thelatter do not encounter thread galling and other problems characteristicof the former.

SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to provide an improvedlocking fastener assembly.

[0010] It is another object to provide a locking fastener assemblycomprising only two components, a nut and a washer.

[0011] It is yet another object to provide a locking fastener assemblyin which secure locking is achieved between a rotatable nut and anon-rotatable washer without the use of separate locking elements.

[0012] It is still another object to provide a locking fastener assemblyincluding a new and improved locking mechanism.

[0013] It is a further object to provide a new and improved lockingmechanism for a locking fastener assembly wherein a locking relationshipis established directly between nut and washer.

[0014] It is yet a further object to provide a locking mechanism for alocking fastener assembly wherein a washer and nut interlock isestablished and a constant bearing load resiliently maintained when theassembly is employed to mount a vehicle wheel.

[0015] The foregoing and other objects of the invention are realized ina locking fastener assembly which comprises only a nut and a washer.Each is formed from medium carbon steel.

[0016] The washer includes a generally cylindrical washer body and aflange extending radially outward from the base of the body. A clampingsurface is formed on the bottom of the flange and washer body base.

[0017] The top of the washer body has an annular, generally sphericallyconcave load bearing surface formed on it. The load bearing surfaceincludes an annularly extending series of inclined bearing faces forminga uniform undulation around the entire surface. A series of plateausurfaces between the inclined bearing faces form the upper peaks of theundulation. A series of valley surfaces between the inclined bearingfaces form the valleys of the undulation. Each of the plateau and valleysurfaces are spherically concave. Each of the inclined bearing faces isalso spherically concave. The height of the plateau surface above thevalley surface is slightly greater than the clearance between thethreads in the nut and those on a vehicle axle spindle, for example,when the locking fastener assembly is in place.

[0018] The slightly concave washer body clamping surface on the bottomof the washer forms what approximates a shallow frustum of a cone. Thissurface is inclined upwardly from the outer periphery of the washerflange of its bottom toward the washer body axis.

[0019] The washer flange has a plurality of slots formed inwardly fromits outer edge, at regular intervals around the flange. These slotspermit intervening flange sections to resiliently flex, albeit onlyslightly, when the washer clamping surface is forced against an outerbearing race and is under the desired load.

[0020] An ear is formed inwardly of the base of the washer body,opposite the flange. The ear is designed to slide axially through asuitably formed slot in the threaded end section of an axle spindle toprevent the washer from rotating relative to the spindle as the nut isthreaded onto this end section. In the alternative, a flat may be formedon the spindle and a corresponding flat formed inwardly of the washerbody.

[0021] The nut includes a generally cylindrical nut body which isinternally threaded. A hexagonal surface is formed around the peripheryof the nut body to permit gripping the nut with a wrench.

[0022] Depending from the nut body is a unitarily formed annular skirt.The skirt is adapted to extend axially into the generally cylindricalbody of the washer and then be formed outwardly under an undercutshoulder within the washer body to loosely, but securely, hold thewasher and nut together.

[0023] The bottom of the nut body, above the skirt, has an annular,generally spherically convex load bearing surface formed on it. The loadbearing surface includes an annularly extending series of inclinedbearing faces forming a uniform undulation around the entire surface. Aseries of plateau surfaces between the inclined bearing faces form thelower peaks of the undulation. These plateau surfaces are sphericallyconvex, with the same radius as the valley surfaces on the washer's loadbearing surface. Each of the inclined bearing faces is also sphericallyconvex, with the same radius as the bearing faces on the washer's nutbearing surface.

[0024] When the nut is threaded onto the axle spindle, the washer ispushed freely in front of it without rotating, until the slightlyconcave, frusto-conical clamping surfaces engage on the ends of theflange sections the inner bearing race of the outer bearing assemblysupporting the wheel hub. Further axial travel of the washer is thenresisted by the bearing race, first relatively lightly while the bearingraces move closer together and then relatively firmly as the bearingraces reach their operating positions.

[0025] Meanwhile, the peaks on the opposed undulating load bearingsurfaces ride over each other with greater and greater difficulty as theload increases. Finally, they can slip past each other only when theflange sections on the washer begin to resiliently flex. The nut is thensecurely prevented from counter-rotating and loosening by theinterlocking bearing faces and the resilient pressure of the washer.

[0026] In locked relationship, the spherically convex plateau surfacesin the load bearing surface of the nut seat flush against correspondingspherically concave valley surfaces in the load bearing surface of thewasher. Also, the convex inclined leading bearing faces on the nut seatflush against the concave inclined trailing bearing faces of the washerand prevent the nut from backing off.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention, including its construction and operation, isillustrated more or less diagrammatically in the drawings, in which:

[0028]FIG. 1 is an end view of a vehicle axle and wheel hubincorporating a locking fastener assembly embodying features of thepresent invention;

[0029]FIG. 2 is a sectional view taken along line 2-2 of FIG. 1;

[0030]FIG. 3 is an exploded perspective view of a nut and washer inposition to be assembled;

[0031]FIG. 4 is a bottom plan view of a locking washer assembly,partially in section;

[0032]FIG. 5 is a top plan view of a locking washer assembly, partiallyin section;

[0033]FIG. 6 is a side elevational view of a locking washer assembly,partially in section;

[0034]FIG. 7 is a plan view of a quarter segment of overlying opposedbearing surfaces on a nut and washer, showing their relationship to eachother circumferentially;

[0035]FIG. 8 is an enlarged sectional view of an arcuate portion (on an18° arc in the present illustration) of the mating bearing surfaces inthe assembly, the view depicting curved bearing faces and surfaces asstraight because of this;

[0036]FIG. 9 is a side elevational view of the nut, showing the convexcurvature of its inclined bearing faces; and

[0037]FIG. 10 is a side sectional view through the washer, showing theconcave curvature of its inclined bearing faces.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0038] Referring to the drawings, and particularly to FIGS. 1 and 2, anaxle assembly for an automotive vehicle is shown generally at 10. Theaxle assembly 10 includes a spindle 12 which extends horizontally from avertically oriented plate 14. The plate 14 forms the outer face of afitting 16 which is mounted in a conventional manner on the frame (notshown) of a vehicle.

[0039] Seated for rotation on the spindle 12 is a wheel hub 20. Thewheel hub 20 includes a generally cylindrical body 22 formed unitarilywith a radially extending flange 24. A plurality of studs 26 extendaxially from the flange 24 near its periphery. The studs 26 are employedin a conventional manner to mount a wheel (not shown) on the wheel hub20.

[0040] The wheel hub 20 is seated on the spindle 12 on an inner rollerbearing assembly 28 and an outer roller bearing assembly 29. The innerbearing assembly 28 is located on a cylindrical inner section 31 of thespindle 12 and is retained between a shoulder 33 on the spindle and anopposing shoulder 35 inside the body 22 of the wheel hub 20. The outerbearing assembly 29 is located on a cylindrical outer section 37 of thespindle 12 and is seated against a shoulder 39 inside the hub body 22and against a frusto-conical spacer 41 encircling the taperedmid-section 43 of the spindle on the inner end of the bearing assembly.

[0041] The outer bearing assembly 29 is held in operating relationshipagainst the shoulder 39 and spacer 41 by a locking fastener assembly 50embodying features of the present invention. In this regard, the lockingfastener assembly 50 is threaded onto the threaded outer end section 45of the spindle 12 and seats against the inner bearing race 47 of thebearing assembly 29.

[0042] The locking fastener assembly 50 is threaded onto the end section45 of the spindle 12 to take up undesired play in the bearing assemblies28 and 29 and, accordingly, hold them both in proper operating positionand relationship. If the fastener assembly 50 is threaded too snuglyagainst the bearing race 47, the bearing assemblies 28 and 29 will bothbe over-loaded and their operating life shortened. If the fastenerassembly 50 is not threaded sufficiently far onto the end section 45,the bearing assemblies 28 and 29 will have too much play and theiroperating life will be shortened. The locking fastener assembly 50 isdesigned to be turned onto the threaded end section 45 of the spindle 12to a desired position and then held securely in that position by lockingforces exerted internally of the assembly according to the invention.

[0043] Referring now to FIGS. 3-10, the locking fastener assembly 50comprises only two components, a nut 52 and a retainer washer 54. Bothare forged steel elements. In the preferred embodiment shown here, thenut 52 is formed from medium carbon steel and then heat treated to anaverage hardness of 33 on the Rockwell C scale. The washer is alsoformed from medium carbon steel and then heat treated to an averagehardness of 39 on the Rockwell C scale.

[0044] The nut 52 comprises a nut body 62 which is internally threadedat 64 for receipt of the threaded end section 45 of the spindle 12.Externally, the nut body has a hexagonal shape surface 66 which isadapted to mate with a standard socket wrench for tightening andloosening the nut 52.

[0045] Extending generally axially away from the nut body 62 at theinner end of the internal threads 64 is a skirt 68. The skirt 68 extendsaway from the generally spherically convex load bearing surface 72 ofthe nut body 62 and through the retainer washer 54. The skirt 68 isformed outwardly in a manner hereinafter discussed so that it retainsthe washer 54 on the nut 52 in loose relationship.

[0046] According to the invention, the generally spherically convex loadbearing surface 72 on the nut body 62 is, in fact, an annularlyundulating surface extending entirely around the nut body, as best seenin FIG. 9. The surface 72, which will hereinafter be described ingreater detail, may be formed using any desired technique but, in thepresent instance, is formed by cold forging using a die insert which ismachined to the desired complex curvature shape using conventional ballend mill techniques.

[0047] The washer 54 comprises an annular washer body 82 having agenerally spherically concave load bearing surface 84 at its inner endand a clamp surface 86 for engaging the aforedescribed inner bearingrace 47 at its outer end. The clamp surface 86 is formed on the outerend face 88 of the body 82 and a washer flange 92 which encircles it.

[0048] The generally spherically concave load bearing surface 84 on theinner end of the washer body 82 is also an angularly undulating surfaceextending entirely around the washer body, as best seen in FIG. 10. Thesurface 84, which will hereinafter be described in greater detail, isalso formed by cold forging using a die pin which is machined on one endto the desired complex shape using conventional ball end milltechniques.

[0049] The outer end face 88 of the body 82 and flange 92 on the washerbody 82 is slightly frusto-conical in shape. The end face 88 is inclinedupwardly at an angle of approximately 3° from the outer periphery 94 ofthe flange to the inner periphery 96 of the body 82.

[0050] The flange 92, which is approximately 0.12 inches (3.0 mm) thickin the washer 54 illustrated, is segmented by six cut-outs 98 around itscircumference so as to define six radially extending flange sections102. The end face 88 is also interrupted by six Vee-shaped, depressions104 extending radially inwardly from corresponding cut-outs 98. Thiseffectively separates the annular clamp surface 86 into six arcuateclamp surface segments 106, the arcuate outer extremities of which,between cut-outs 98, are able to resiliently flex axially of the washer54. Although the flange 92 is shown here separated into six flangesections 102, however, it should be understood that the inventioncontemplates using a greater or lesser number depending upon the size ofthe washer and thickness of the flange.

[0051] Extending radially inwardly from the end face 88 is an ear 108.The ear 108 is of a size and shape suitable to slide loosely in anaxially elongated slot 49 formed on one side of the threaded endsections 45 of the spindle 12. As will hereinafter be further discussed,when the fastener assembly 50 is installed, the ear 108 and slot 49cooperate to prevent rotation of the washer 54 relative to the spindle12. Although the use of ear 108 and slot 49 cooperation to preventwasher 54 rotation is shown here in the context of vehicle hub 20mounting, it should also be understood that the invention contemplatesthe use of other conventional means for preventing washer rotation.

[0052] Referring now in greater detail to the generally sphericallyconvex load bearing surface 72 on the nut body 62, it comprises a seriesof oppositely inclined side bearing faces, 73 with peaks in the form ofplateau surface segments 74 and with narrow valley bottoms at lines 75.Each pair of side bearing faces 73 with a valley floor line 75 betweenthem forms what approximates an inverted Vee shape.

[0053] The plateau surface segments 74 are formed in the cold forgingprocess so that they are all convex and lie on the surface of animaginary sphere whose center is on the axis of the nut body 62. In thenut 52 which is illustrated, and which has an outside diameter betweenflats of the hexagon of approximately 2.125 inches (54 mm) and a nutbody 62 thickness of approximately 0.50 inches (12.7 mm), the radius ofthat sphere is 2.00 inches (50.8 mm).

[0054] Each inclined side bearing face 73 is also formed so that it isconvex and is curved both radially and circumferentially of the nut body62. As will hereinafter be described, these convex surfaces 73 areformed so as to be complementary with corresponding concave side bearingfaces in the generally spherically concave load bearing surface 84 onthe washer body 82.

[0055] In the nut body 62 illustrated, the height of each plateausurface segment 74 formed by adjacent side bearing faces 73, i.e., thevertical height from the valley floor lines 75, is 0.015 inches (0.38mm). According to the invention, and for reasons hereinafter discussed,this height is slightly greater than the clearance between the threadson the end section 45 of the spindle 12 and the threads 64 in the nutbody 62 when they are assembled.

[0056] Referring now in greater detail to the generally sphericallyconcave load bearing surface 84 on the washer body 82, the surfacecomprises a uniform series of inclined side bearing faces 116 with peaksin the form of plateau surfaces 118 and with wider valley floors in theform of valley surfaces 122. Each pair of inclined bearing faces 116with a valley surface 122 forms what approximates a Vee shape.

[0057] The valley floor surfaces 122 are formed in the forging processso that they are all concave and lie on the surface of an imaginarysphere whose center is on the axis of the washer body 82. The radius ofthat sphere is 2.00 inches (50.8 mm). As such, it will be seen that theplateau surface segments 74 on the nut body 62 are perfectlycomplementary in shape to the valley floors 122 on the washer body 82.

[0058] In the washer body 82 illustrated, the height of each plateausurface segment 118, i.e., the vertical height from the valley floor122, is slightly less than 0.015 inches (0.38 mm). As a result, when nut52 and washer 54 are seated against each other in nested relationship,each plateau surface segment 74 will seat uniformly on a correspondingvalley floor 122 while opposed inclined bearing faces 73 and 116 will beslightly separated.

[0059] When the opposed bearing surfaces, surface 72 on the nut body 62and surface 84 on the washer body 82, are nested in lockingrelationship, however, the trailing inclined bearing faces 116 of thewasher body 82 seat against the leading inclined bearing faces 73 on thenut body 62. Because these opposed inclined bearing faces 73 and 116 areformed so as to be complementarily convex and concave, respectively, andall their radii of curvature axially of the assembly 50 and from itsaxis equal those of the aforementioned valley floor surfaces 122,locking surface contact is maintained between them even if the nut 52and washer 54 are not precisely parallel to each other because the nutdoes not thread perfectly squarely onto the spindle.

[0060] The nut 52 and washer 54 are assembled to create the lockingfastener assembly 50 by inserting the skirt 68 of the nut through thewasher in the manner best seen in FIG. 6. The skirt 69 is then dimpledoutwardly by forming at six evenly spaced locations 69 around itsperiphery so as to underlie an annular inward projection 83 in thewasher body and, accordingly, loosely but securely connect the nut 52and washer 54 while permitting the nut to rotate freely relative to thewasher.

[0061] In use for securing a wheel hub 20 on the spindle 12 in an axleassembly 10 for a truck or some other vehicle, for example, after awheel hub 20 has been seated on its supporting bearing assemblies 28 and29, a fastener assembly 50 is slipped over the threaded end section 45of the spindle 12 so that the ear 108 in the washer 54 slides along theslot 49 in the spindle until the internal threads 64 in the nut body 62engage the external threads on the spindle. The nut 52 is then threadedonto the spindle 12 by hand until the clamp surface 86 on the washerbody 82 engages the inner bearing race 47. As the nut 52 rotates whilebeing threaded onto the spindle 12 in this way, the washer 54 movesaxially with it but is prevented from rotating because its ear 108 isaxially slidable in, but rotationally fixed by, the slot 49 in thespindle.

[0062] As the nut 52 rotates, its undulating bearing surface 72 slipseasily over the opposed undulating bearing surface 84 on the washer 54as the nut pushes the washer before it. When the clamp surface 86engages the inner bearing race 47, however, further rotation of the nutis resisted with greater and greater effect by the interlocking effectof the opposed inclined side bearing faces on the nut 52 and washer 54,respectively, as the nut turns and axial pressure builds up in thebearing assemblies 28 and 29. As this pressure builds up, the flangesections 102 begin to flex, creating a resilient force tending to keepthe inclined bearing faces of opposed side bearing surfaces 72 and 84 ininterlocked relationship.

[0063] The flange sections 102 are designed to resiliently flex throughan axial distance which is slightly greater than the clearance betweenthe spindle 12 threads and nut body 62 threads. Because the flangesections 102 are able to flex slightly more than this clearance, thewasher 54 can move axially under load to some degree without degradationof the lock between washer 54 and nut 52. At the same time, because theheight of the plateau surface 118 above the valley surface 122 in thewasher body 82 is slightly greater than the clearance also, once alocking relationship is established with the proper preload the nut 52and washer 54 can move slightly relative to each other without looseningthe fastener assembly 50.

[0064] When a predetermined torque setting is reached in turning the nut52 of the locking assembly 50 onto the spindle 12, the bearingassemblies 28 and 29 are properly preloaded. The locking assembly 50 canthen be relied upon to resist all axial forces tending to cause the nut52 to back off. Increased axial load from he wheel hub 20 merely causesthe nut 52 and washer 54 to become more securely locked together againstrelatively rotation. Only by applying loosening torque to the nut 52again, as with a hex wrench, can the locking assembly 50 be removed.

[0065] Although the invention in a locking fastener assembly has beendescribed in the context of a vehicle wheel hub mounting arrangement, itshould be understood that it might be otherwise employed. Its two-partsimplicity, rugged construction, virtually fail-proof action and lowmanufacturing cost may make it very attractive in many applications.

[0066] While a preferred embodiment of the invention has been described,it should be understood that the invention is not so limited, andmodifications may be made without departing from the invention. Thescope of the invention is defined by the appended claims, and alldevices that come within the meaning of the claims, either literally orby equivalence, are intended to be embraced therein.

1. A locking fastener assembly, comprising: a) a fastener nut and a fastener washer rotatable relative to each other about a common axis; b) an annular washer bearing surface on said nut and an annular nut bearing surface on said washer, said annular bearing surfaces being axially opposed to each other; c) each of said annular bearing surfaces having a plurality of inclined bearing faces oriented circumferentially and forming portions of an undulating annular bearing surface; and d) a clamping surface on said washer.
 2. The locking fastener assembly of claim 1 further characterized in that: a) said washer includes a washer body and a flange extending radially outwardly from said washer body; b) at least a portion of said clamping surface being formed on washer flange.
 3. The locking fastener assembly of claim 2 further characterized in that: a) said washer flange comprises a series of flange segments extending annularly around said washer body; b) said flange segments being slightly flexible axially of said washer;
 4. The locking fastener assembly of claim 2 further characterized in the: a) said clamping surface is normally slightly frusto-conical in shape.
 5. The locking fastener assembly of claim 1 further characterized in that: a) said inclined bearing faces which are opposed to each other on respective nut and washer are curved both radially and circumferentially of said assembly and are complementary to each other.
 6. The locking fastener assembly of claim 1 further characterized in that: a) each of said nut and said washer is formed of steel.
 7. The locking fastener assembly of claim 1 further characterized in that: a) said nut includes a nut body on which said washer bearing surface is formed, and an annular skirt extending from one end of said nut body adjacent its bearing surface; b) said washer including a washer body having an aperture extending therethrough; c) said skirt extending through said aperture when said nut and washer are assembled; and d) at least some portion of said skirt being deformed outwardly after said nut and washer are assembled so as to loosely hold said washer on said nut.
 8. The locking fastener assembly of claim 7 further characterized in that: a) said nut body is internally threaded so that it can be turned onto an externally threaded member; b) said washer body including an element formed in said aperture for preventing said washer from rotating when said nut is turned onto said threaded member.
 9. A locking fastener assembly, comprising: a) an internally threaded fastener nut, including a fastener body having an annular skirt depending therefrom; b) a fastener washer including an annular washer body having a flange extending radially outwardly therefrom; c) said annular skirt extending loosely through said washer whereby said nut is freely rotatable relative to said washer before said fastener assembly is mounted; d) an annular washer bearing surface on said nut body and an annular nut bearing surface on said washer body e) said washer bearing surface on said nut body being convex and including a series of shallow peaks and valleys extending around said nut body so as to create undulations including annularly inclined bearing faces; f) said nut bearing surface on said washer body being concave and including a series of shallow peaks and valleys extending around said washer body so as to create angular undulations with annularly inclined bearing faces; g) said flange having an annular clamping surface thereon and being capable of flexing slightly axially of said washer body.
 10. The locking fastener assembly of claim 9 further characterized in that: a) said inclined bearing faces are each somewhat spherical in shape and complementary to each other when seated in locking relationship against each other.
 11. The locking fastener assembly of claim 9 characterized in that: a) the height of the peaks in one of said washer bearing surface and said nut bearing surface is greater than the height of the peaks in the other of said washer bearing surface and said nut bearing surface.
 12. A locking fastener assembly, comprising: a) a fastener nut and a fastener washer connected to each other in such a manner that they can be rotated relative to each other about a common axis; b) an annular washer bearing surface on said nut and an annular nut bearing surface on said washer, said annular bearing surfaces being axially opposed to each other; c) each of said annular bearing surfaces including a plurality of inclined bearing faces oriented circumferentially and forming what approximates an undulating annular bearing surface.
 13. The locking assembly of claim 12 further characterized in that: a) said washer includes an axially resilient element for holding said bearing surfaces in engagement with each other.
 14. The locking fastener assembly of claim 13 further characterized in that: a) said axially resilient element is capable of flexing through a predetermined distance axially of said fastener assembly; b) the effective maximum height of each of said undulating surfaces being less than said predetermined distance.
 15. The locking assembly of claim 13 further characterized in that: a) one of said annular bearing surfaces is convex and the other is concave relative to a plane perpendicular to said common axis.
 16. The locking assembly of claim 14 further characterized in that: a) said inclined bearing faces on one of said nut and said washer being concave and on the other being convex.
 17. The locking fastener assembly of claim 12 further characterized in that: a) one of said annular bearing surfaces having plateau between alternating pairs of adjacent inclined bearing faces; b) the other of said annular bearing surfaces having valley floors between alternating pairs of adjacent inclined bearing faces; c) said plateau and floors being segmentally spherical about a common center when said assembly is in locking relationship. 